3.4. Production of human tissue plasminogen activator (tPA) by
CHO 1-15 cells
We next examined whether reciprocal mixing affects the production of a
target protein. In this study, we compared the production of tPA by CHO
1-15 cells in EE and RM bioreactors, operated at Pv = 36
W/m3 (equivalent to 2.0 Hz (80 mm/s) for reciprocal,
and 140 rpm for EE rotary). Activity of tPA increased during exponential
phase in both the bioreactors, along with increasing cell number (Figs.
6, 7). After passing through the late exponential or early stationary
phase (at approximately 100–120 h), CHO 1-15 cells in reciprocal
bioreactor were found to produce tPA activity 1.3–1.5 times higher than
in EE bioreactor (Fig. 7). It implied that the total amount of tPA
protein produced in reciprocal bioreactor was approximately 1.5 times as
much as in EE bioreactor. Moreover, cell viability in EE bioreactor
rapidly decreased after approximately 200 h (Fig. 6A). The culture
medium in EE bioreactor was found to contain undesirable impurity, such
as cell debris derived from destroyed or dead cells. Therefore, some
definitive advantages do exist in reciprocal-mixing bioreactor.